This invention relates to an improved rubber tired carrier for use in connection with material handling systems. More particularly, the invention is directed to a rubber tired carrier having an adjustable width. Adjustability is advantageous inasmuch as the carrier is easily transported when the width is narrowed yet the carrier provides sufficient stability to the system when the width is expanded in material handling applications.
While this invention is particularly directed to the art of material handling, and will thus be described with specific reference thereto, it will be appreciated that the invention may have usefulness in other fields and applications. For example, the invention may also have usefulness in connection with earthmoving equipment--such as cranes and dozers--and snow removal equipment.
A wide variety of material handling systems are known. These systems use a carrier--two types of which are typical--to support the machine/equipment actually used to handle material or scrap.
The first type of carrier is a rubber tired carrier. Rubber tired carriers are useful in situations where transporting machinery to and from job sites is necessary. This is because rubber tired carriers generally have a width narrow enough to comply with highway standards and have conventional wheel and axle assemblies as well as conventional steering mechanisms. When such a system, though, is being used to handle materials, the wheel base of the rubber tired assemblies is alone too narrow to provide sufficient stability. Consequently, separate outriggers which extend from the carrier are utilized. Sufficient lateral stability is thus provided to the carrier because an effective width greater than the wheel base of the rubber tired assemblies is created by the outriggers. Depending on the circumstances of use, the outriggers vary in size and strength.
In addition, known rubber tired carriers have axles which limit maneuverability and suspension systems which cause rocking when the carrier is moving from one location to another. This is especially troublesome when the carrier is moving and carrying a heavy load because the rocking becomes increasingly exaggerated and could cause tipping of the carrier.
The second type of carrier used is a crawler track carrier. Crawler tracks are useful in some applications but have limited adaptability. For example, crawler tracks provide good stability, skid steering, and improved traction over conventional tired assemblies. However, a crawler track design is not conducive to on-road transport situations.
Further, known track style carriers typically utilize a drive sprocket and an idler sprocket. The idler sprocket is the sprocket that usually is recommended by manufacturers to carry larger loads. Thus, the operator must always be aware of the orientation of the carrier so that the bulk of the load can be positioned over the idler sprocket instead of the drive sprocket.
Recently, regulations have been enacted requiring that scrap yards utilize asphalt or concrete pavement instead of gravel or dirt. As a result, both of the above-referenced types of carriers have become difficult to use in scrap yard applications. More specifically, rubber tired carriers utilizing outriggers do not operate well on concrete or asphalt because, when the outriggers are in use, the load is concentrated on only four points thus causing cracking of the underlying pavement or embedding of the outriggers therein. The crawler track design is also not desirable because the tracks can tear up and cause damage to hard surfaces such as asphalt or concrete.
The present invention contemplates an improved rubber tired carrier which resolves the above-referenced difficulties and others.